2008

Bonding by Hydroxide-Catalyzed Hydration and Dehydration

The solution acts to form a bond within a settling time, during the early part of which one can separate and/or move the substrates to align them more precisely. Regardless of whether substrates to be bonded are capable of forming silicatelike networks or have precisely matching surface figures, the settling time can be tailored via the concentrations of hydroxide ions and silicate material in the bonding solution. For example, for bonding silica-based materials, the settling time can be tailored between about 40 minutes at one extreme of composition (hydroxide but no silica) and tens of seconds at the other extreme of composition (silica with a smaller proportion of hydroxide).

If the surface figures of the substrates do not match precisely, bonding could be improved by including a filling material in the bonding solution. The filling material could be in the form of particles, foam, and/or a liquid. The filling material facilitates bridging of gaps between the substrate surfaces. Preferably, the filling material should include at least one ingredient that can be hydrated to have exposed hydroxyl groups and that can be chemically linked, by hydroxide catalysis, to a silicatelike network. The silicatelike network could be generated in situ from the filling material and/or substrate material, or could be originally present in the bonding material.

This work was done by Dz-Hung Gwo of Stanford University for Marshall Space Flight Center. For more information, contact Sammy Nabors, MSFC Commercialization Assistance Lead, at This email address is being protected from spambots. You need JavaScript enabled to view it.. Refer to MFS-32082.

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